As anyone used to reading my posts would know that I am a minimalist - I think there's way too much micro-analysing and over-thinking on things trumpet,
So, with that being said - I don't oil my valves individually. Maybe once a week, I blow some oil from my mouthpipe through the entire horn and out the bell. Been doing this since Jr. H.S. and that was a long time ago.
I do think, though, that the oil makes a difference, so use that judiciously. (And even speaking of minimalist oil, for several years my oil was a mixture of 3-in-One oil and White Kerosine. Fuggataboutit.)